Thermo-electric element.



known deoxidizer,

'unrrnn STATES PATENT curios.

ALBERT L. MARSH, or nn'rnorr, MICHIGAN, ASSIGNOB. 'ro Ho's'KI-Ns MANUFACTURING COMPANY, OF DETROIT, MICHIGAN, A CORPORATION 03 MICHIGAN.

rnnnmontncrnro ELEMENT.

No Drawing.

Patented Oct. 21', 1913;

Application filed September 30, 1912. Serial'No. 723,197.

To all whom, it may concern:

Be it known that I, ALBERT L. MAnsn, a citizen of the United States,.residing at Detroit, in the county of Wayne and State of Michigan, have invented a new and useful Thermo-Electric Element, of which the following is a specification. i

My invention relates to a novel thermoelectric element.

Pure nickelhas long been used as a positive element in thermo electric couples, and it is known to give a good millivoltage when associated with any of the known negative elements. However, nickel is of a peculiar unreliable nature. The causes for this fault of nickel areobscure in their nature and'not fully understood, but in practice it is found that while occasionally a pure nickel 'element will have a normal life, almost always it develops extremely brittle spots so that it breaks under the ordinary handling to which it is necessarily subjected in practice. Particularly, when used in fuel furnaces, does this difiiculty appear, and I am therefore inclined to believe that the cause of the increase of brittleness is the presence of reducing gases which seem to enter into some sort of a chemical union, possibly of a very unstable nature with the nickel. It is known that nickel unites at certain temperatures with carbon monoxid, and a reaction of this. character may have. something to do with' the well-known treachery of nickel for the purpose intended.

I have discovered that the addition of silicon to the nickel to a large extent eliminates this difliculty of nickel without effecting or materially changing its 'millivoltage when'used as a thermo-electric element. I

prefer to add the silicon in from 3 to 5%, and with my present knowledge of the art of rolling and drawing metals I have not succeeded in satisfactorily working any ele ment in which the silicon runs above 7%, although I do not'intend to state that that is the highest limit to which it can be added and still form a workable alloy, for the reason that the art of working metals is constantly advancing and from time to time metals are rolled, which were considered absolutely unworkable in the past.

To get the best result, I find it desirable to add in addition to the silicon a quantity of aluminum, or some other wellmanganese,

slightly in excess of the amount required for deoxidizing purposes.-

This slight excess serves merely to render the metal more easily workable and there are doubtless other metals than deoxidizers which will have this same effect. In other Words, the nickel-silicon alloy seems to be slightly cold short, and the addition of a slight amount of manganese or aluminum, and probably many other metals, removes this shortness. v

.I have heretofore patented a positive thermo-velect-ric element consisting of nickel and aluminum. 'The nickel-aluminum alloy is considerably better than the-nickel, but the treacherous and unreliable character of the nickel is more thoroughly removed by the addition of silicon than by theaddition of.

aluminum. On the other hand, in the present state of my hiowledge, I am of the opinion that the silicon-nickel cannot be run at as high temperatu'reas can the nickelaluminum and, therefore, I prefer to use the present element for temperatures up to 2000 F., or thereabout, and the nickelaluminum element for a higher temperature. These statements, however, of comparative values are not intended to be absolute in their nature for the reason that they are based only on my present experience, and in practice, I find that variations in the purity of the metal, the manner of working them and the like, bring out from time to time new properties or capacities. As a positive statement I can go nofurther than to say that the present element is very satisfactory in temperatures up t02000 F., that it is very much better than pure nickel, and that in practice'at such temperatures at the presout time I am using it in preference to the nickel-aluminum.

While I have described the preferred composition of my element, I do notintend to be limited to elements composed solely of the metals specified for the reason that it will be obvious to those skilled in the art,

that other metals may be added to the nickelsilicon without very material change,

although doubtless some metals can be added which seriously upset its thermo electric properties. It is undoubtedly true, however, that either iron or cobalt can be used in considerable percentages, as additions to the nickel-silicon alloy described without being.

seriously detrimental, although I have found in practice that cobalt changes the electromotive force temperature curve of a couple in which it is employed, so as to make the couple less desirable for electrical measurement purposes. Doubt-less, other materials can be added in the same way, without departing from the spirit of my invention.

What I elaimas new and desire to secure by Letters Patent is:

1. A positive thermo-electric element consisting of nickel and silicon.

2. A positive thermo-electric element consisting of nickel and silicon, the silicon in proportion of from 3 to 5%. 1

' 3. A positive thermo-electric element con-' 5 sisting of nickel and silicon, with an added quantity of an auxiliary adapted to'remove shortness.

4. A positive thermo-electric element consisting of an alloy of nickel and silicon, with an added quantity of manganese as an auxiliary to remove shortness. v

5. A positive thermo-electric element consisting of nickel and silicon, the silicon in the proportion of from 3 to 5%, with an added quantity of manganese to remove shortness. ALBERT L. MARSH. In presence of J. G. ANDERSON,-

J. LANDEsMAN. 

